Short Message Service (SMS) is a mechanism of delivery of short messages over the mobile networks and provides the ability to send and receive text messages to and from mobile telephones. SMS was created as part of the GSM Phase 1 standard. Each short message is up to 160 characters in length for Latin character messages. The 160 characters can comprise of words, numbers, or punctuation symbols. Short messages can also be non-text based such as binary. The Short Message Service is a store and forward service and messages are not sent directly to the recipient but through a network SMS Center. This enables messages to be delivered to the recipient if their phone is not switched on or if they are out of coverage at the time the message was sent—so called asynchronous messaging just like email. Confirmation of message delivery is another feature and means the sender can receive a return message notifying them whether the short message has been delivered or not. In some circumstances multiple short messages can be concatenated (stringing several short messages together).
In addition to SMS, Smart Messaging (from Nokia), EMS (Enhanced Messaging System) and MMS (Multimedia Messaging Service) have emerged. MMS adds images, text, audio clips and ultimately, video clips to SMS (Short Message Service/text messaging). Nokia created a proprietary extension to SMS called ‘Smart Messaging’ that is available on more recent Nokia phones. Smart messaging is used for services like Over The Air (OTA) service configuration, phone updates, picture messaging, operator logos etc. Smart Messaging is rendered over conventional SMS and does not need the operator to upgrade their infrastructure. SMS eventually will evolve toward MMS, which is accepted as a standard by the 3GPP standard. MMS enables the sending of messages with rich media such as sounds, pictures and eventually, even video. MMS itself is emerging in two phases, depending on the underlying bearer technology—the first phase being based on GPRS (2.5G) as a bearer, rather than 3G. This means that initially MMS will be very similar to a short PowerPoint presentation on a mobile phone (i.e. a series of “slides” featuring color graphics and sound). Once 3G is deployed, sophisticated features like streaming video can be introduced. The road from SMS to MMS involves an optional evolutionary path called EMS (Enhanced Messaging System). EMS is also a standard accepted by the 3GPP.